Most dogs enjoy chewing on things, although preferences vary as to the hardness of the substances favored. Some dogs like to chew on very hard materials such as cow bones, wood and nylon, while others prefer softer chews such as polyurethane or rubber. Still others favor freeze dried snacks. Some dogs due to their age, may not be able to chew on very hard substances. Young dogs may have insufficiently developed teeth, while old dogs may have diseased gums or may have lost some of their teeth.
Many indigestible objects are given to dogs as a chew and although the dogs may enjoy chewing thereon, the objects are often swallowed in whole or in part. Once swallowed, these objects or fragments thereof may have an adverse effect on the dog's digestion and may become impacted in the dog's intestinal tract with life-threatening consequences. By way of example, dog chews have been marketed which utilize an ethylene copolymer which can be fractured by the chewing action of a dog, and when ingested can block the dog's stomach passages.
Other edible dog chews have been marketed which have a comparatively short shelflife and therefore must be replaced by retail outlets at frequent intervals. Yet other prior art dog chews are lacking in structural integrity whereby they are susceptible to breakage during handling and shipping.
The prior art is replete with disclosures directed at converting starch or related materials into a molded or shaped article. The following discussion therefore provides a brief chronological overview of the development of such technology as it has appeared in the patent literature over the past several decades.
For example, starting with U.S. Pat. No. 2,602,755 (1952), entitled “Thermoplastic Compositions of Water-Soluble Cellulose Ethers” it was disclosed that powdered methyl cellulose of a water soluble variety could be blended with a particular narrow range of mixtures of propylene glycol and glycerin to provide compositions which could be molded or extruded when pressure was applied at temperatures of 150 degrees to 170 degrees C., without decomposition. This was then followed by U.S. Pat. No. 3,137,592 (1961), entitled “Gelatinized Starch Products” which described a method of preparing homogenous gelatinized starch products, which method was characterized by intense mechanical working or shearing of the starch at elevated temperatures and pressures in the presence of a minor-proportion of a starch-swelling agent. The method goes on to disclose the use of a screw-type extruder, along with water as the preferred starch-swelling agent or plasticizer due to its low cost and relatively low boiling point.
Attention is next directed at U.S. Pat. No. 3,038,895 (1962), entitled “Water-Dispersible Partially Substituted Derivatives of Amylose” which describes a means for producing an amylose derivative which was readily dispersed in water without the need to exceed temperatures above 130 degrees C., which dispersion was identified as “viscosity stable”, thereby forming films of excellent water resistance. Shortly thereafter, in U.S. Pat. No. 3,074,803 (1963), entitled “Molding Starch Composition”, a method was disclosed for preparing molded starch compositions, which method focused on the blending of high melting point fatty acid esters with starch which blends are then said to provide a composition relatively free of oil build-up along with what was said to be a minimum of starch dusting.
This was followed by U.S. Pat. No. 3,117,014 (1964), entitled “Amlaceous Compositions for Shaped Articles and Process” which described starch compositions which are said to flow under heat and pressure which compositions comprise a derivative of amylaceous material, a plasticizer for said derivative, and water, wherein the amount of water is between 1.0–20% by weight. Turning next to U.S. Pat. No. 4,076,846 (1978), entitled “Protein-Starch Binary Molding Composition and Shaped Articles Obtained. Therefor” an edible, water-soluble thermoplastic molding composition comprising a starch material is disclosed, along with a neutral inorganic alkali salt of protein material, water, an edible plasticizer, an edible lubricant, and other additives. Such compositions were said to have excellent moldability and processibility when subjected to various common plastics processing techniques, such as compression molding, transfer molding, extrusion molding, blow molding, inflation molding, injection molding, vacuum forming, pressuring forming, heat sealing, etc.
More recent disclosures include U.S. Pat. No. 4,673,438 (1987), entitled “Polymer Compositions and Injection Molding”. This disclosure states that capsules and other shaped products can be formed from a starch composition comprising starch, with a molecular mass range of 10,000 to 20,000 Daltons, along with a water content from 5–30% by weight. The recited process using an injection molding machine requires that one maintain a starch/water composition at a water content of 5–30% by weight of the composition under controlled conditions of temperature and pressure, heating said starch/water composition at elevated pressure above its glass transition temperature and melting point while maintaining said water content to form a melt, further heating and plasticizing said molten starch/water composition to dissolve the starch in the water to form what is stated to be an essentially molecularly dispersed solution of the melt. This is followed by injecting the starch/water melt into a mold cavity while maintaining a predetermined water content, and cooling the composition in the mold to form a molded product at a temperature below the glass transition temperature of the composition and ejecting the molded product from the mold.
In U.S. Pat. No. 4,738,724 (1988), entitled “Method for Forming Pharmaceutical Capsules from Starch Compositions” injection molded capsules of starch are disclosed, for pharmaceutical applications, which method, similar to the '438 patent discussed above, recites that one first provide a starch/water mixture having a water content in the range of about 5% to 30% by weight based on the weight of starch and water. This is followed by heating the starch/water composition at elevated temperatures above its glass transition temperature and melting point while maintaining the water content to form a melt, followed by further heating and plasticizing said molten starch-water composition to dissolve the starch in the water followed by injection molding of the plasticized starch at elevated temperature and pressure into a mold, and forming a multi-chambered configuration, and ejecting the molded capsule from the mold.
U.S. Pat. No. 5,405,564 (1995), entitled “Method of Forming Shaped Articles From Pre-Processed Starch” recites a process of forming shaped articles from starch. The method is described as having surprisingly established that in the process of injection molding starch, there are two important steps that are preferably separated. That is, this disclosure recites that one must first heat a starch/water mixture wherein the water content is about 10% to about 20% by weight with respect to that of said starch, in a closed volume to a temperature within the range of about 120 degrees C. to about 190 degrees C. at a pressure corresponding to the vapor pressure of water at the used temperature and up to about 150 times 10 sup. 5 N/m. sup. 2, to form a melt, wherein said melt is extruded and cooled to a solidified and granulated product. This is then followed by heating such solid starch composition, wherein the water content of said solid composition is about 10% to about 20% by weight with respect to that of said starch, in the screw barrel of an injection molding machine or an extruder, at a temperature of from about 80 degrees C. to about 200 degrees C., and at a pressure of from about zero to about 150 times 10 sup. 5 N/m sup. 2 for a time long enough to form what is termed as a melt of destructurized starch, transferring said melt of destructurized starch to a mold or extruding said melt of destructurized starch while maintaining the water content in the range of from about 10% to about 20% by weight with respect to that of the composition, and cooling said melt of destructurized starch in said mold or outside said extruder to form a solid shaped article.
Attention is also directed to the following United States Patents and copending applications, commonly owned by the assignee of the present invention and included herein by reference: U.S. Pat. No. 5,476,069; U.S. Pat. No. 6,093,427 entitled “Vegetable Based Dog Chew”; U.S. Pat. No. 5,827,565 entitled “Edible Dog Chew”; U.S. Pat. No. 5,941,597 entitled “Carrot-Based Dog Chew”; U.S. Pat. No. 6,180,161 filed Jul. 14, 1998 entitled “Heat Modifiable Edible Dog Chew”; U.S. Pat. No. 6,126,978 entitled “Improved Edible Dog Chew”; U.S. Pat. No. 6,110,521 entitled “Wheat & Casein Dog Chew With Modifiable Texture”; U.S. Pat. No. 6,093,441 entitled “Heat Modifiable Peanut Dog Chew”; U.S. Pat. No. 6,159,516 entitled “Method of Molding Edible Starch”; U.S. Pat. No. 6,586,007 entitled “Health Chew Toy”; U.S. Pat. No. 6,274,182, entitled “Animal Chew”; U.S. Pat. No. 6,067,941 entitled “Animal Chew” and U.S. Pat. No. 6,098,571 entitled “Treat Dispensing Toy”.
In addition to starch and vegetable-containing dog chews, plastics such as polyurethane, nylon and others may also be molded for form items for dogs to chew on.
Pet toys such as dog chews may be produced in the form of strips or toys or even bone shapes, generally having a larger end and smaller shaft to allow the dog to easily pick them up. Dogs generally will hold a dog chew between their paws in order to chew it and this requires easy access to the chew to maintain interest.
Therefore, dog chews may be provided which due to their molded shape stand on a base with at least one leg extending upward for easy access by the dog. These shapes may comprise multiple extensions or legs some of which may also serve as the base. While shapes of these types are more easily accessed by the dog, they are expensive to tool and hardly efficient for packaging and shipping. The nesting density of the chews, especially if packaged individually, is quite low making costs high.
Accordingly, a need exists for an improved pet toy or dog chew design which can either be molded in a collapsed state and expanded when purchased, molded in an expanded shape then collapsed for storage and shipping and expanded when ready for use, or which may be assembled from separately molded components optionally prepared from different compositions or flavors that can be engaged into a base.